The scope of this proposal is to develop a novel pre-clinical therapeutic strategy with a candidate drug for future clinical testing to treat or prevent Alzheimer's disease (AD). AD affects a growing number of individuals worldwide and there is no cure for it. 5-Lipoxygenase (5LO) is an enzyme abundantly present in the central nervous system (CNS), where its activation depends on the presence of a membrane associated protein called FLAP (5-LO activating protein). In the brain, FLAP-dependent 5LO activation increases with aging, one of the strongest risk factors for developing AD. Interestingly, these levels are even higher in AD brains compared with controls. On the other hand, recently we have shown that genetic absence of 5LO enzymatic activity results in a significant reduction of Amyloid 2 (A2) levels in an animal model of AD. Taken together these data suggest an involvement of this pathway in the AD pathogenesis, and support our central hypotheses: FLAP/5LO enzymatic pathway plays a functional role in AD development; its pharmacological modulation represents a novel AD therapeutic target. The objective of this proof-of-principle study is to validate FLAP as a novel and functionally important molecular target in the neurobiology of AD. With this pre-clinical type of studies we want to test the hypothesis that FLAP pharmacological inhibition will ameliorate the AD-like neuropathology and behavioral deficits of a transgenic mouse model of AD. To achieve this goal, we will use a selective FLAP inhibitor, i.e. MK-591, in the following specific aims: Specific Aim 1: Test the hypothesis that early FLAP pharmacological inhibition will delay and or prevents the development of AD-like neuropathology and behavioral deficits in young APP transgenic mice. Specific Aim 2: Assess the efficacy of FLAP pharmacological inhibition in APP transgenic mice after the AD-like neuropathology and behavioral deficits are established. With these studies we intend to complete the initial step in the pipeline for the pre-clinical development of FLAP inhibitors as potential therapeutics for AD. If we demonstrate that MK-591 administration results in a modulation (decrease) of brain amyloidosis, and improvement of behavioral impairments in this AD model, our findings will represent the biologic basis for a subsequent and more comprehensive project submission (i.e., UO1) where several different FLAP inhibitors will be tested and compared for efficacy in this as well as in other AD models. As part of this future research program we will also focus on the pre-clinical optimization (doses, efficacy) and testing of any of the identified lead compounds in individuals with a clinical diagnosis of mild cognitive impairment (MCI) and AD. These studies, if successful, could ultimately lead to an investigation new drug (IND) application to the Food and Drug Administration.